cbs 5's dr. kim mulvihill hs of a lifelong >>> a bay area athlete's battle with lung cancer has inspired a unique journey. >> a lifelong friendship and the spectacular finish and honor of that friendship that's just days away. >> reporter: joe costello was just 22 when she died from lung cancer in 2010. it's how she lived that lives on. >> i do think that last year of jo's life although it was her most difficult and challenging, in many ways it could be the best year of her life. she did so many wonderful, amazing things and lived life to its fullest. >> reporter: best friends since kindergarten in san francisco,. >> i'm using my lungs to run from new york city to san francisco. >> reporter: the 24-year-old harvard grad is spreading a simple message: anyone can get lung cancer, even nonsmokers like jill. >> the reason i'm doing this is for jill is because i have that drive. >> reporter: kelsey took off from times square on july 30th and has spent 4 months on the road. at the wheel, sidney ford wh